Gamma-monolactone of 4-hydroxysuberic acid, its salts and esters, and the salts and amides of 4-hydrosuberic acid, their preparation and use



2,849,457. Patented Aug. 26, 1958 GAMMA-MONOLACTONE F 4-HYDROXYSU- BERICACID, ITS SALTS AND ESTERS, AND THE SALTS AND AMIDES OF 4-HYDROSU- BERICAGED, TI-EIR PREPARATION AND USE Howard E. Holmqnist, Wilmington, Del.,assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., acorporation of Delaware No Drawing. Application June 21, 1956 Serial No.592,738

11 Claims. (Cl. 260.-343.6)

This invention relates to novel chemical processes and to new organicchemical compounds. More particularly, this invention relates to a newmonolactone acid, its salts and its esters and to salts and amides ofits open-chain parent acid, and to methods for their preparation andconversion of these new products to open-chain polyhydric alcohols.

According to my copending U. S. patent application Ser. No. 579,459,filed on April 20, 1956, 1,8-octanedioic acids and 1,8-octanediols areobtained when the dilactone corresponding to C H O [A-bifuran]-5,5'-dione, is hydrogenated at a temperature within the rangeof 150 C. to 325 C. in contact with a copper chromite catalyst. Theaforementioned C l-I 0 dilactone is obtained by reacting acetylene withcarbon monoxide over a cobalt carbonyl catalyst, as disclosed andclaimed in the copending patent application of J. C. Sauer, Ser. No.432,599, filed May 26, 1954, now abandoned, of which Ser. No. 549,155,filed November 25, 1955, is a continuation-in-part.

It is an object of this invention to provide novel chemical processesand new organic chemical compounds. A further object is to provide a newmonolactone acid, its esters and salts, and salts and amides of itsopen-chain parent acid. A still further object is to provide novelmethods for preparing the aforementioned compounds. Another object is toprovide a novel method for preparing carbalkoxypropylbutyrolactones andfor converting them to open-chain saturated polyhydric alcohols. Stillanother object is to provide a new method for preparing a straight-chainaliphatic polyhydric alcohol useful in preparing polyesters. Otherobjects will appear hereinafter.

These and other objects of this invention are accomplished by providingthe new monolactone acid of 4- hydroxysuberic acid, salts and esters ofsaid monolactone acid, and salts and amides of 4-hydroxysuberic acid.This invention also includes novel methods for the preparation of thesenew compounds and conversion thereof to polyhydric alcohols,particularly of the monolactone acid and esters to 1,4,8-octanetriol.

The new monolactone acid of this invention is gamma-(omega-carboxypropyl) butyrolactone. This monolactone acid, its estersand salts correspond to the formula wherein R is hydrogen, hydrocarbon,preferably of up to seven carbon atoms, such as aryl or alkyl,especially lower alkyl, i. e., of 1 to 5 carbon atoms, or a metal orsalt-forming group, as an amino group. When R is alkyl, the monolactoneesters are gamma-(omega-carbalkoxypropyl) butyrolactones.

Alkali metal salts of the monolactone acid, gamma-(omega-carboxypropyl)butyrolactone, are obtained by treating the lactoneacid at ordinary temperatures with aqueous alkali, and the open-chainparent 4-hydroxysuberic acid,

HOOC-(CHah-CH-(CHQa-OOOH is obtained in the form of its alkali metalsalt by treating the monolactone acid,gamma-(omega-carboxypropyl)butyrolactone with aqueous alkali followed byheatmg.

Amides of the open-chain 4-hydroxysuberic acid are obtained by reactingammonia or a primary or secondary amine with the monolactone ester,gamma-(omega-carboalkoxypropyl)butyrolactone.

Conveniently the monolactone acid is obtained directly by hydrogenationof the unsaturated dilactone C H O at temperatures from 75 to 275 C. andpressures of from 1000 to 10,000 lb./ sq. in., over nickel in dioxane orother inert liquid organic reaction medium. The monolactone ester, alongwith an alkyl 4-(2-tetrahydrofuryl)- butanoate, is obtained by effectingthe hydrogenation in the presence of an alcohol or ester.

In a convenient way for preparing the monolactone acid,gamma-(omega-carboxypropyl) butyrolactone, starting with the unsaturateddilactone, [A -bifuran]- 5,5-dione, a pressure reactor is charged withthe unsaturated dilactone, an inert liquid organic reaction medium, suchas dioxane, and at least 1%, by weight of the dilactone, of an activenickel catalyst. The charged reactor is swept with oxygen-free nitrogen,placed on an agitating rack, hydrogen is injected, and the chargemaintained between 75 and 275 C. with agitation and under a pressure of1000 to 10,000 lb./sq. in. After reaction is complete, as evidenced bycessation of pressure drop, the reactor is opened, discharged, and thecontents filtered. The filtrateis subjected to fractional distillationto isolate the desired products. Other methods, however, can be used toisolate the desired products than fractional distillation.

The invention is illustrated in its specific preferred embodiments asfollows:

Example I Fraction Weight, g.

6670/0.9 mm 2. 1.4438, less dense than water. 70120/0.7-0.9 mm 2.1.4521.

5 3 1.4539, denser than water. 7

Fraction 1 was redistilled at C./0.8 mm. (11

1.4424) and corresponds to ethyl 4-(2-tetrahydrofury1)- butanoate, C H Ohaving the structural formula:

3 mm. or 122 C./0.6 mm. A sample of this fraction was redistilled at 127C./0.7 mm., n 1.4540, and from its elemental data corresponds togamma-(omega-carbethoxypropyl) butyrolactone, C H O having thestructural formula:

ODQ-(CH2)3C O O C2 5 Analysis.Calcd for C H O C, 59.98; H, 8.05; M. W.,200; Sap. Eq. 100, 100. Found: C, 60.17, 60.29; H, 8.13, 8.36; M. W.,200, 200; Sap. Eq., 103, 103.

Infrared analysis showed bands at 6.65, for lactone carbonyl and at5.75; for ester carbonyl.

Methyl acetate can be used instead of ethyl acetate to obtain the methylester, gamma-(omega-carbomethoxypropyl)butyrolactone.

Example 11 Pres- Fraction B. P., sure, WgtJg.

Fractions 7 and 8 crystallized to the hexahydrodilactone, tetrahydro[2,2' bifuran] 5,5 (2H,2'H)- dione. This amounted to a 14% yield.

Fraction 1 was redistilled and had an n 1.4403, and corresponded toethyl 4-(2-tetrahydrofuryl)buta- 110316, CmH O Analysis.--Calcd for C HO C, 64.49; H, 9.74; M. W., 186. Found: C, 63.60, 63.58; H, 10.10,10.31; M. W., 192.

Fractions 4, 5 and 6 were refractionated under 0.9 mm. pressure to givea main fraction boiling at 138- 141 C. under 0.9 mm. pressure, 11,1.4547, corresponding to gamma-(omega-carbethoxypropyl)butyrolactone.

Analysis.Calcd for C H O C, 59.98; H, 8.05. Found: C, 60.19; H, 8.28.

Methanol can be used instead of ethanol to obtain the methyl ester,gamma-(omega-carbomethoxypropyl)- butyrolactone.

Example III To a one-liter stainless steel pressure vessel was added 90g. of once recrystallized [A -bifuranl-5,5'- dione, 700 ml. of dioxaneand alloy-skeleton nickel. The reactor was repeatedly evacuated andflushed with nitrogen until air was removed. The reaction mixture washeated at 75100 C. under 1000 lb./sq. in. hydrogen pressure until 0.8mole of hydrogen were absorbed and further absorption ceased. Thecatalyst was removed by filtration and the excess dioxane removed at 100C. under reduced pressure. Distillation of the remaining oil through an8" Vigreux column gave 74 g. of a colorless oil boiling at 180183.5/0.8mm. pressure.

Analysis showed the product to contain gamma- (omega-carboxypropyl)butyrolactone and tetrahydro- 4 [2,2'-bifuranl-5,5-(2H,2H)-dione in essentially equal amounts.

Benzylamine (0.77 g.) dissolved in one ml. of dioxane was added to 2 ml.of the reduction product obtained as above, dissolved in 4 ml. ofdioxane. Addition of diethylether caused precipitation of a white,crystalline product, 1.12 g. (56% yield). Two recrystallizations fromdioxane gave a product melting at 101 to 102 C. which analyzed asfollows:

AIZLZZYSISrCZllCd for C15H21NO4 C, H, 7.58%; N, 5.02%. Found: C, 64.62%;H, 7.55%; N, 4.94%.

Example IV To a stainless steel pressure vessel was added 30 g. of pure'[A -bifuran]-5,5-dione, 200 ml. of decahydronaphthalene, and 3-5 g. ofalloy-skeleton nickel. The vessel was closed, evacuated, and flushedwith nitrogen until free of air. The suspension was heated at 200 C. and3000 1b./sq. in. hydrogen pressure until hydrogen absorption ceased. Theresulting mixture was filtered and the filtrate distilled under reducedpressure to give 12.1 g. of a colorless oil.

Analysis of this oil indicated that it contained approximately -94%tetrahydro [2,2 bifuran] 5,5- (2H,2'H)-dione and 10-15% ofgamma-(omega-carboxypropyl) butyrolactone.

A solution was prepared by dissolving 8 g. of hexamethylenediamine in 50ml. of dioxane, which corresponds to a concentration of 0.13 g. of thediamine per ml. of solution.

Another solution was prepared by dissolving 10.2 g. of the oilyreduction product, obtained as above, in 15 ml. of dioxane. To thissolution there was added 26.8 ml. of the hexamethylenediamine solutionwith stirring and cooling to maintain the temperature of the reactionmixture at ca. 22 C. The white solid which formed was separated byfiltration and washed with diethyl ether. The dried product weighed 2.72g., which corresponds to a 57% yield on the total weight of reactants.After recrystallization from 35 ml. of absolute ethanol with diethylether, the white product, which is the hexamethylenediammonium salt ofthe lact'one acid, gammaiclargnega-carboxypropyl)butyrolactone, meltedat 118 to Analysis.-Calcd for C H N O C, 57.37%; H, 8.76%; N, 6.08%.Found: C, 57.13%; H, 8.86%; N, 6.06%, 6.07%.

Example V A solution of 8.5 g. ofgamma-(omega-carboxypropyl)butyrolactone, 0.2 g. of p-toluenesulfonicacid in 250 ml. of ethanol was refluxed for 50 hours. The solution wasneutralized with solid sodium bicarbonate and the product distilled at138-140 C./2 mm. to give 6.7 g. (68%) of the ethyl ester.

The fraction boiling at 139141 C./2 mm. weighed 4.8 g. and constitutedthe main cut. It had an 21 1.4552 and corresponded togamma-(omega-carbethoxypropyl)butyrolactone.

Methanol can be used instead of ethanol to obtain the methyl ester,gamma-(omega-carbomethoxypropyl)- butyrolactone.

Example VI A solution of 2.8 g. ofgamma-(omega-carbomethoxypropyl)butyrolactone, in 25 ml, of 28% aqueousammonia was heated overnight on asteam bath. The residue solidified whenit was triturated with hot methyl ethyl ketone.

The tan powder thus obtained weighed 0.6 g. It was recrystallized twicefrom ethanol to give the diamide of 4-hydroxysuberic acid, meltingsharply at 151 C.

AnaIysis.-Calcd for C H O N C, 51.05; H, 8.57; N, 14.88. Found: C,51.27; H, 8.77; N, 14.37.

The unsaturated dilactone corresponding to C H O lA -bifuranl-5,5-dione,used in the above examples was prepared by charging into a 400 cc. steelpressure reactor 26 g. of acetylene, 200 ml. of acetone, and 1.5 g. ofdicobalt octacarbonyl. The mixture was heated with carbon monoxide at1000 atm. pressure for 14-17 hours. The product was filtered and thebrown solid was extracted with ethyl acetate for 24 hours. The extractwas permitted to crystallize and the crystalline material was separated,and dried at room temperature. There was obtained 20 g. of theunsaturated dilactone, C H O M. P. 229 C. after severalrecrystallizations from acetic acid. This dilactone exists in cis andtrans isomeric forms. These two structural isomers yield suberic acidwhen hydrogenated with platinum in acetic acid. The normal orlow-melting form, M. P. 230-237" C., is the trans form and thehigh-melting form, M. P. 240- 248 C., is the cis form. The formulae ofthese structural isomers of [A -bifuran]-5,5'-dione are as follows:

Low-melting or trans form Highanelting or cis form Although the exampleshave illustrated batch operation, it is to be understood that theprocess can be carried out as a continuous or semi-continuous up-fiow,downfiow, no-current, or counter-current vapor or liquid phaseoperation, with recovery of unconverted reactants for recycling.

The hydrogenation of the [A -bifuran]-5,5'- dione is elfected at 75 C.to 275 C. and pressures of from 1000 to 10,000 lb./sq. in. or more.

The hydrogenation can be eifected with any active nickel catalyst. Thenickel catalyst may be in the form of stabilized or pyrophoric metal, asthe oxide, or salt. Elementary nickel in pyrophoric or stabilized statecan be prepared by methods yielding the active form of the metal attemperatures below 150 C., or by reducing a salt, oxide, or hydroxide ofthe metal with hydrogen at temperatures in the range of 400-700 C. Thepyrophoric metal may be stabilized by exposure to an oxidizingatmosphere under conditions such that the temperature of the catalyst ismaintained below 50 C.

Pyrophoric nickel may be conveniently made by extracting with alkali thealkali-soluble component of an alloy of nickel with an alkali-solublemetal or by reducing a nickel salt with sodium naphthalene as describedin U. S. Patent 2,177,412. The nickel catalyst may be unsupported orsupported. The extender may be added during the catalyst preparation orit may be formed in situ. Suitable supports are alumina, silica, pumice,charcoal, etc. The example which follows illustrates preparation of atypical alloy-skeleton nickel catalyst.

Three hundred parts of a finely divided alloy composed of equal parts ofnickel and aluminum is added with stir ring, over a period of one andone-half hours, to a solution of 342 parts of sodium hydroxide in 1590parts of distilled water maintained at 50 C. The supernatant liquid isthen decanted off and the catalyst is washed with distilled water untilit is free from alkali.

The product is pyrophoric and it may be stabilized as follows:

The aqueous sludge of the product is placed in a rotating vessel. Thevessel is sealed, the air is exhausted by means of a vacuum pump and themass heated under vacuum until all free water is removed. The vessel isthen cooled continuously with cold Water and a small amount of air isblown through the dry mass at such a rate that the temperature of thedry mass does not exceed C. After 2 hours a sample of the dry product isno longer pyrophoric. The catalyst is found by analysis to consist of37% nickel, of which is in the elementary state, and 43% A1 0 Thecatalyst therefore probably consists of partially oxidized nickelsupported on alumina.

The amount of nickel catalyst is at least 1% by weight of the [A-bifuranl5,5-dione being hydrogen ated. Since the rate of hydrogenationis improved by increasing the catalyst concentration, usually an amountis employed which is at least 5% and preferably 10% by weight of the [A-bifuranl-5,5'-dione being hydrogenated.

As shown in the examples, hydrogenation of with nickel in dioxane yieldsas principal products a mixture ofgamma(omega-carboxypropyl)butyrolactone and the meso and racemic formsof tetrahydro-[2,2'-bifuran]- 5,5'-(2H,2H)-dione. The latter materialseparates from the mixture as a crystalline phase and the former,together with some dilactone, remains in the oil phase. The oil isdissolved in Water, the aqueous solution is neutralized with sodiumbicarbonate, and the dilactone is extracted with chloroform. Theremaining aqueous solution is acidified and extracted with an organicsolvent. to obtain the acid, which is then distilled through a precisionstill under reduced pressure. In an alternative method for isolating themixture of gamma-(omegacarboxypropyl)butyrolactone and of meso andracemic forms of tetrahydro [2,2'-bifuran] -5 ,5 ZI-LZ'H) -dione the oilis neutralized with saturated aqueous sodium bicarbonate and theneutralized mixture is cooled in an ice bath. The crystalline phase thatforms is the mixture of meso and racemic forms oftetrahydro-[2,2'-bifuran]- 5,5-(2H,2'H)-dione, and is isolated byfiltration. The remaining aqueous phase contains the sodium salt ofgamma-(omega-carboxypropyl)-butyrolactone. The free acid is isolatedfrom the sodium salt by acidification, followed by extraction with anorganic solvent, and distillation of the solvent. Nickel, cobalt, iron,and other metal salts can be made by reacting the sodium salt insolution with a salt of the metal whose salt is desired.

The examples have illustrated preparation of gamma-(omega-carboxypropyl)butyrolactone andgamma-(omega-carbethoxypropyl)butyrolactone by hydrogenating repectivelyin dioxane or decahydronapthalene, and in ethanol or ethyl acetate asthe liquid organic reaction medium. It is to be understood that thedioxane can be replaced by tetralin, cyclohexane, isooctane, and otherliquid organic compounds which are unreactive with carboxyl groups andthat in place of ethanol and ethyl acetate there can be used otheralkanols, preferably lower alkanols of from 1 to 5 carbon atoms, andesters of such alkanols with aliphatic carboxylic acids, preferably of 1to 5 carbon atoms. When these alkanols and esters are used there areobtained the corresponding gamma-(omega-carbalkoxypropyl)butyrolactones.Thus, with methanol or methyl acetate there is obtainedgamma-(omegacarbomethoxypropyl)butyrolactone; with butanol or butylpropionate there is obtainedgamma-(omega-carbobutoxypropyl)butyrolactone; with propanol or propylvalerate there is obtained gamma-(omega-carbopropoxypropyl)-butyrolactone; etc.

The amount of reaction medium can be varied over wide limits. Usually,however, an amount is used which is at least stoichiometricallyequivalent to the [A bifuran]-5,5'-dione being hydrogenated.

The gamma-(omega-carbalkoxypropyl)butyrolactones,gamma-(omega-carboxypropyl)butyrolactone and its salts and the4-(Z-tetrahydrofuryl)butanoic acid esters produced in accordwith thisinvention as well as the salts and amides of 4-hydroxysuberic acid, areuseful for conversion to the eight carbon straight chain polyols. Thesepolyols are useful for preparing polyesters which have utility asprotective coatings, components of coating. compositions, and the like.The conversion of the gamma- (omega-carbethoxypropyl)butyrolaetone tothe polyol, 1,4,8-octanetriol employing a copper chromite catalyst, isillustrated below:

Example A A solution of 4.1 g. ofgamma-(omega-carbethoxypropyl)butyrolactone in 150 ml. of dioXane washydrogenated over copper barium chromite (1.5 g.) at 225 C. and 3000lb./sq. in. hydrogen pressure for 3 hours. The viscous product (3.7 g.)was distilled at 151l64 C. (0.5 mm), to give a principal fractionboiling at 161 164 C. (0.5 111111.). The chemical composition of thisfraction shows it to be 1,4,8-octanetriol.

Analysis.Calcd for C H O C, 59.23; H, 11.18. Found: C, 58.32, 58.57; H,10.89, 11.14.

Infrared spectral analysis shows strong absorption in the hydroxylregion at 305 which is consistent with the 1,4,8-octanetriol structure.7

The 1,4,8-octanetriol obtained in accord with Example A above, being apolyhydric alcohol, is useful for preparing polyesters by reaction withcarboxylic acids by methods well known to those skilled in the art.Thus,

with polycarboxylic acids such as adipic and sebacic acids, there areobtained polymeric polyesters which are useful as protective coatings,as components of coating compositions, and the like.

As many apparently widely difierent embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that this invention is not limited to the specificembodiments thereof except as defined in the appended claims.

The embodiments of the invention in which an exelusive property orprivilege is claimed are defined as follows:

1. A gamma (omega carbalkoxypropyl(butyrolactone.

2. Gamma (omega carbethoxypropyl)butyrolac tone.

3. Gamma-(omega-carboxypropyl)butyrolactone.

4. Process for preparing an oxygen-containing heterocyclic compoundwhich comprises heating and hydrogenating [A -bifuranl-5,5'-dione withhydrogen in contact with a nickel hydrogenation catalyst at atemperature in the range of 75 to 275 C. and under a pressure of 1000 to10,000 lb./sq. in., in the presence of a liquid organic reaction mediumselected from the group consisting of dioxane, decahydronaphthalene,tetralin, cyclohexane, isooctane, lower alkanols, and lower alkanolesters of lower alkanoic acids, and obtaining as the resulting productat least one oxygen-containing heterocyclic compound selected from theclass consisting of gamma (omega carboxypropyl)butyrolactone andgammaomega-carbalkoxypropyl) butyrolactone.

5. Process for preparing a gamma-(omega-carbalkoxypropyl)butyrolactonewhich comprises heating and bydrogenating [A -bifuran]-5,5'-dione withhydrogen in contact with a nickel hydrogenation catalyst at atemperature of to 275 C. and under a pressure of 1000 to 10,000 lb./sq.in. in the presence of a lower alkanol as reaction medium and obtainingas the resulting product a gamma-(omega-carbalkoxypropyl)butyrolactone.

6. Process for preparing a gamma-(omega-carbalkoxypropyl)butyrolactonewhich comprises heating and hydrogenating [A -bifuranl-5,5'-di0ne withhydrogen in contact with a nickel hydrogenation catalyst at atemperature of 75 to 275 C. and under a pressure of 1000 to 10,000lb./sq. in. in the presence of a lower alkanol ester of a lower alkanoicacid as reaction medium and obtaining as the resulting product a gamma-(omega-carbalkoxypropyl)butyrolactone.

7. Process for preparing gamma-(omega-carbethoxypropyl)butyrolactonewhich comprises heating and hydrogenating [A -bifuran]-5,5'-dione withhydrogen in contact with a nickel hydrogenation catalyst at atemperature of 75 to 275 C. and under a pressure of 1000 to 10,000lb./sq. in. in the presence of ethanol as reaction medium and obtainingas the resulting product gammaomega-carbethoxypropyl butyrolactone.

8. Process for preparing gama-(omega-carbethoxypropyl)butyrolactonewhich comprises heating and hydrogenating [A -bifuran]-5,5-dione withhydrogen in contact with a nickel hydrogenation catalyst at atemperature of 75 to 275 C. and under a pressure of 1000 to 10,000 lb./sq. in. in the presence of ethyl acetate as reaction medium andobtaining as the resulting productgamma(omega-carbethoxypropyl)butyrolactone.

9. Process for preparing galmma-(omega-carboxypropyl)butyrolactone whichcomprises heating and hydrogenating lA -bifuran]-5,5-dione with hydrogenin contact with a nickel hydrogenation catalyst at a temperature of 75to 275 C. and under a pressure of 1000 to 10,000 lb./sq. in., in thepresence of dioxane as reaction medium and obtaining as the resultingproduct gammaomega-carboxypropyl) butyrolactone.

10. A chemical compound selected from the class consisting of thegamma-monolactone of 4-hydr0xysuberic acid, salts and esters of saidgamma-monolactone, and salts and amides of 4-hydroxysuberic acid.

11. A gamma(omega-carbalkoxypropyl)butyrolactone wherein the alkoxygroup is a lower alkoxy group of not more than five carbon atoms.

References Cited in the file of this patent Adkins et al.: J. Am. Chem.Soc., 53, pages 1095-7, 1931.

Adkins: Reactions of Hydrogen, Table 54 (page also pages and 138 (1937).

Russell et 2.1.; J. A. C. S., 74, 4543-6 (1952).

4. PROCESS FOR PREPARING AN OXYGEN-CONTAINING HETEROCYCLIC COMPOUNDWHICH COMPRISES HEATING AND HYDROGENATING($2,2''(5H,5''H)-BIFURAN)-5,5''-DIONE WITH HYDROGEN IN CONTACT WITH ANICKEL HYDROGENATION CATALYST AT A TEMPERATURE IN THE RANGE OF 75* TO275*C. AND UNDER A PRESSURE OF 1000 TO 10,000 LB./SQ. IN., IN THEPRESENCE OF A LIQUID ORGANIC REACTION MEDIUM SELECTED FROM THE GROUPCONSISTING OF DIOXANE, DECAHYDRONAPHTHALENE, TETRALIN, CYCLOHEXANE,ISOOCTANE, LOWER ALKANOLS, AND LOWER ALKANOL ESTERS OF LOWER ALKANOICACIDS, AND OBTAINING AS THE RESULTING PRODUCT AT LEAST ONEOXYGEN-CONTAINING HETEROCYCLIC COMPOUND SELECTED FROM THE CLASSCONSISTING OF GAMMA - (OMEGA - CARBOXYPROPYL)BUTYROLACTONE ANDGAMMA-(OMEGA-CARBALKOXYPROPYL)BUTYROLACTONE.